Narrow rows, hoeing and harrowing barley in Denmark

New research paper from Margaret McCollough and Bo Melander of Aarhus University in Denmark recommends narrow rows with inter-row hoeing, but found increased seeding rates did not improve crop yield, and harrowing effects were inconsistent. The Open Access paper is available here.

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While increasing barley density did not increase yields, it did prove to be a reliable strategy for suppressing the growth of pesky intra-row weeds left behind after hoeing! Elevating barley density from 200 to 500 plants per square meter increased the percent reduction of intrarow surrogate weed biomass from 49% to 82%, and intrarow ambient weed biomass from 53% to 99%.

Figure 3. Prediction of percent reduction (%) in intrarow surrogate (gray; Sinapis alba) and ambient weed biomass (black; assorted species) as crop density (plants m−2; barley) increases. Curves are calculated on the basis of parameter estimates in Tables 3 and 4 for two row spacings, 15 cm (RS15) and 20 cm (RS20), and two weed management treatments, receiving no additional weed management treatment (WMTweedy) and preemergence tine harrowing (WMTtineharrow), in 2019 (dotted; EXP2019) and 2020 (solid; EXP2020). All plots received interrow hoeing.